Polymers and use thereof as scale inhibitors

Abstract

Compositions and methods for inhibiting scale are provided. Pursuant to the present invention, a composition for inhibiting scale is provided that includes a carbohydrate polymer having both nitrogen-containing groups and carboxyl groups. The nitrogen-containing groups include amino groups, amido groups and mixtures thereof. The present invention has been found useful for inhibiting scale in industrial waters, such as, pulp bleach plant process waters which contain calcium oxalate and barium sulfate scale.

What is claimed is:  
     
       1. A polymer comprising repeating mer units of the formula:                    
       where X is selected from the group consisting of CO, C(H)OH, and mixtures thereof, R is selected from the group consisting of H, alkyl groups, acyl groups, and mixtures thereof, and n is an integer from 1 to 400,000. 
     
     
       2. The polymer of  claim 1  wherein R is H, CH 3 CO or mixtures thereof. 
     
     
       3. The polymer of  claim 1  wherein R is H. 
     
     
       4. The polymer of  claim 1  wherein R is CH 3 CO. 
     
     
       5. The polymer of  claim 1  wherein the polymer is selected from the group consisting of a polyaminouronic acid, a polyacetamidouronic acid, and mixtures thereof. 
     
     
       6. A method of producing a polymer, the method comprising the steps of: 
       providing a base polymer;  
       oxidizing the base polymer in a solution containing an oxidizing agent; and  
       recovering a polymer comprising repeating mer units of the formula:                    
       where X is selected from the group consisting of CO, C(H)OH, and mixtures thereof: R is selected from the group consisting of H, alkyl groups, acyl groups, and mixtures thereof, and n is an integer from 1 to 400,000. 
     
     
       7. The method of  claim 6  wherein said base polymer is selected from the group consisting of chitin and chitosan. 
     
     
       8. The method of  claim 6  wherein said base polymer has a formula:                    
       where n is an integer from 1 to 400,000. 
     
     
       9. The method of  claim 6  wherein said base polymer has a formula:                    
       where n is an integer from 1 to 400,000. 
     
     
       10. The method of  claim 6  wherein the oxidizing agent is selected from the group consisting of hypochlorite, hydrogen peroxide, ozone, N 2 O 4 , activated dimethyl sulfoxide, and N-chlorosuccinimide. 
     
     
       11. The method of  claim 6  wherein said solution containing an oxidizing agent further comprises a catalytic agent. 
     
     
       12. The method of  claim 6  further comprising the step of maintaining a pH level ranging from about 10 to about 12 during said oxidizing. 
     
     
       13. A method for inhibiting scale derived from an industrial water system containing an amount of scale, the method comprising the steps of: 
       providing a polymer comprising repeating mer units of the formula:                    
       where X is selected from the group consisting of CO, C(H)OH, and mixtures thereof; and R is selected from the group consisting of H, alkyl groups, acyl groups, and mixtures thereof; and n is an integer from 1 to 400,000; and adding an effective amount of said polymer to the industrial water system. 
     
     
       14. The method of  claim 13  wherein R is H, CH 3 CO, or mixtures thereof. 
     
     
       15. The method of  claim 14  wherein R is H. 
     
     
       16. The method of  claim 14  wherein R is CH 3 CO. 
     
     
       17. The method of  claim 13  wherein said effective amount of polymer is at least about 2 ppm. 
     
     
       18. The method of  claim 13  wherein said effective amount of polymer is at least about 5 ppm. 
     
     
       19. The method of  claim 13  wherein said effective amount of polymer is at least about 10 ppm. 
     
     
       20. The method of  claim 13  wherein the scale is calcium oxalate, barium sulfate, or mixtures thereof.